1. Field of the Invention
The present invention relates to a cooler, an X-ray tube apparatus having the cooler, and a method for operating the cooler.
2. Description of the Related Art
In general, an X-ray tube apparatus such as an X-ray computed tomography (CT) apparatus is used in a medical or industrial diagnosis system. The X-ray tube apparatus has a pedestal, and a revolving body that is rotatably mounted on the pedestal. For example, as is disclosed in Jpn. Pat. Appln. Publication No. 2000-164390, an X-ray tube that radiates X-rays, and a cooler that cools the X-ray tube are attached to the revolving body.
The X-ray tube has a housing. The X-ray tube has an X-ray radiation unit that radiates X-rays, and a circulation unit that is filled with cooling fluid and flows the cooling fluid to cool the X-ray radiation unit in the housing.
The cooler is arranged in the X-ray tube apparatus so as to improve the performance and efficiency of the X-ray tube apparatus. The cooler has another circulation unit that is different from the circulation unit of the X-ray tube. This other circulation unit is so formed as to deliver cooling fluid to the circulation unit of the X-ray tube, and cool down the cooling fluid which is taken in after circulating through the circulation unit, and deliver the cooling fluid to the circulation unit again.
The circulation unit and the other circulation unit are coupled by a coupler. The coupler has a plug that has its one end closed, and a socket that has its one end closed. The plug and the socket are coupled such that both the closed ends are coupled. Accordingly, both the one ends are opened, forming a flow path for cooling fluid. For example, the plug is coupled to the circulation unit of the X-ray tube, and the socket is coupled to the other circulation unit of the cooler.
The cooler may be set in environments in which the temperature changes when being transported. For example, the temperature changes between −25° C. and 70° C. Accordingly, the cooling fluid comes to be expanded and contracted. Furthermore, when using the X-ray tube apparatus, the temperature of the cooling fluid rises in order to cool down the X-ray radiation unit. Thus, the cooling fluid comes to be expanded.
When the cooling fluid is expanded, the cooling fluid may leak from coupling portions, etc., of components configuring the X-ray tube apparatus. When the cooling fluid leaks, air may infiltrate the circulation unit or another circulation unit from leakage portions. Furthermore, in the cooler, in case the cooling fluid is contracted, the closed state of one end of the socket is dissolved, and air may infiltrate the circulation unit from the socket. The X-ray absorption rate in the cooling fluid is different from that in air. Accordingly, air undesirably passes in front of X-rays radiated from the X-ray radiation unit, which prevents correct diagnosis.